This invention relates to pictorial display devices with a matrix of gas discharge cells in general and more particularly to an improved device of this nature.
Such a pictorial display device with which auxiliary anodes for controlling the rows and control electrodes for the brightness control of the columns are associated, and with an auxiliary discharge path between the cathode and the auxiliary anodes as well as an electron accelerating path between the control electrodes and the anode is described in U.S. Pat. No. 3,956,667. The hole matrix formed by a plate of insulating material divides the common discharge space into an auxiliary discharge space of relatively great length for operation with low voltage for the gas discharge current and a second space with short path length and high field intensity for accelerating the electrons. The insulating hole matrix serves as the carrier for the auxiliary anodes associated with the rows of the matrix. If desired, the control electrodes for the brightness control of the columns of the matrix can be arranged on the opposite flat side of the matrix. Cathode and anode are designed with large areas.
The electrons, which are generated in the linewise controlled auxiliary glow discharge and are moved toward the auxiliary anode, are accelerated and imaged, controlled dot by dot in the following discharge path of high field intensity by the correspondingly subdivided control electrode, onto the anode, which can preferably be realized as a coherent screen electrode, and on which the electrons are imaged as defined picture elements. If a row of the auxiliary anodes is driven, the discharge burns uniformly along the entire electrode, while the negative glow covers a region, the area of which is determined by the well known dependence of the current density at the cathode on the gas pressure. A wedge shaped discharge is particularly advantageous for the overall arrangement.
It is known that the form of the discharge is substantially affected by the nature of the gas and the electrode surface. It has further been found that the square shape of the glow at the anode can be disturbed by still other influences. It has further been found that the desired wedge shaped discharge takes place only when it makes a transition to the anamalous form, i.e., if the discharge current is increased to the extend that the entire cathode is covered.